CD-ROM Volume and File
Structure

Besides defining their physical structure and the raw
recording structure of the bits, computer storage media
require some specification of File Layout and
Volume Structure. Essentially, they need a
directory structure so that files can be laid out on the
disc and organized by name. This structure for CD-ROM is
commonly known as "ISO-9660", and sometimes still called
the "High Sierra" standard.

The following quote is from the ECMA-130 CD-ROM
specification.

In October 1985 a number of industrial and software
companies in the USA invited experts to participate in
the elaboration of a working paper describing a proposal
for the volume and file structure of such disks. The
result of this work ... was a report dated May 1986 and
known as the “High Sierra Group” proposal.
This proposal was submitted to ECMA for their
consideration [which] led to the issue in December 1986
of Standard ECMA-119 [Volume and File Structure of
CDROM for Information Interchange] which has been
adopted by ISO as ECMA Standard ISO 9660.

So ECMA-119 is the same as ISO-9660. The term "High
Sierra", by the way, comes from Del Webb's High Sierra
Hotel and Casino in Reno, Nevada, the place where the
meeting was held. There is also an extended standard
called ECMA-168 which "can be used for both CD-ROM and
CD-WO media for interchanging files. [ECMA-168] is seen
as a revision and extension of ECMA-119 for CD-ROM
applications because it has eliminated several
restrictions and performance problems of ECMA-119."
[ECMA-168, Brief History]. Copies of all ECMA standards
are available at no charge from http://www.ecma.ch/